Fireproof porous material and method of making same



Patented Mar. 24, 1931 UNITED STATES PATENT OFFICE HARRY HOPKINSON, 0F LANSDOWNE, PENNSYLVANIA, ASSIGNOB, BY DIRECT AND .MESNE ASSIGNMENTS, TO THE BRUNSENE COMPANY OF MASS, OF WATEBTO'W'N,

MASSACHUSETTS FIREPROOI POROUS MATERIAL AND METHOD OF MAKING SAME No Drawing.

The present invention relates to the fireproofing of porous material and more particularly to the method of treating combustible material so that it is rendered noninflammable. M

Some of the objects of the present invention are to provide a method of rendering ordinarily combustible material fireproof and fire resistant even though exposed to weather conditions; to provide a material which retains fire resisting properties after being immersed in water; to'prov'ide a method of treating canvas, cotton goods and other combustible fabrics and textiles to convert such material into a fireproof product having subthe original material; to provide a method of fireproofing combustible materials whereby the material is not rotted or disintegrated by the composition when exposed to weather conditions; to provide a fireproof material which is non-brittle and can be readily handled without breaking and cracking; to provi de a method of fireproofing material which 1S permanent; to provide a material, suitable for tents, awnings, covers, paulins, and other uses inwhich the fire hazard has been eliminated; and to provide a fireproof material which can be readily cut, shaped and sewed.

The invention broadly considered comprehends the impregnation of a porous material with a salt or salts possessing fireproofing qualities and which salt or salts is or are insoluble in water. The materials generally tobe treated are of a textile nature and the invention is more particularly for use in the fireprooiing of cotton goods inthe form of tent material, awning material, coverings and the like, though its applicability to other materials will be readily apparent and the scope of the invention is not to be restricted because of any reference herein to a specific material used by way of illustration.

the pores of the material; second, by impreg- Application filed October 11, 1928. Serial N0. 811,97'L

nating the material with the solution of a salt that is insoluble in water but soluble in some other salt solution, the latter salt being afterward converted or otherwise destroyed or removed; and, third, by impregnating the material with an emulsion containing an insoluble fireproofing salt and then breaking down the emulsion to leave the insoluble salt in the pores of the material. 5

One way of carrying out the treatment by the first example consists in saturating the material with a soluble lead salt and then treating the saturated material with a soluble chloride whereby the resulting reaction precipitates lead chloride (-or other haloid) in the pores of the material, the lead chloride being not only flame resisting but also very sparingly soluble in water. An additional step in this method consists in subjecting the material to a treatment with a solution of a borate as thereby the fireproofing qualities of the fabric are considerably increased and made more permanent.

The preferred method has been found exceedingly simple and efficient in practice and con sists of passing the material to be treated saturated solution depending upon the weight per square yard of the material to be treated, but in most cases the solution is more nearly saturated than otherwise. This bath is maintained at a relatively high temperature, say for example 208 F., and the material remains immersed therein for periods of time varying with the weight of the material. For an eight ounce piece of goods it has been found this period of immersion should be about three minutes in order to secure the proper saturation of the material. When the material leaves this bath it is passed through suitable rolls to squeeze out excess and surface solution and is then fed into a second bath which is a solution, preferably at room temperature, of aluminum chloride. The percentage of this'aluminum chloride may vary from fifteen percent to saturation desecond bath likewise varies according to the kind and weight of the goods but generally varies from two to five minutes. The reaction of the chloride salt with the previously absorbed lead salt results in the precipitation of lead chloride which is almost insoluble in water and has the required fire resistant properties. After again being subject to a squeezing operation, the treated material can be either dried directly or immersed in a third bath preliminary to the drying step. The third bath treatment is desirable so that the additional step in the method consists in immersing the material in a bath which is a solution of borax maintained in heated condition. The time in this bath varies according to the quality and Weight of the goods but generally is about the same period as that required in the second bath. This borate solution materially increases the fireproof qualities of the material both before and after Weathering. While a borate solution has been specifically mentioned, this third bath may consist of a soluble phosphate, carbonate, tungstate, or fluoride. The effect of this third step is to convert the soluble products of the previous treatment into fire-resisting, water-insoluble products.

Upon removal from this third bath the material is passed through rolls to squeeze out excess solution, after which it may be dried. It is noW not only fully fireproof but rain and exposure to water cannot wash out the salts which give it this desired property.

Having thus described my invention, 1 claim:

1. The method of fireproofing a porous material which comprises impregnating the material with a solution of'a lead salt, and then treating the material with a solution of a haloid.

2. The method of fireproofing a porous material which comprises impregnating the material with a solution of a lead salt, and then treating the material with a solution of a metallic chloride.

Signed at Philadelphia, county of Philadelphia, State of Pennsylvania, this 10th day of October, 1928.

HARRY HOPHNSON. 

